The field of invention is devices which preclude unauthorized operation of a valve; and more particularly to a device which attaches to a handle which operates the valve and inhibits movement of that handle.
A ball valve is a common type of mechanism for controlling the flow of a fluid through a pipeline. Such a valve has a housing with an inlet opening and an outlet opening to which sections of the pipeline are attached. Within the housing is a ball that has an aperture therethrough. The ball is attached to one end of a stem which extends through an opening in the housing and has a handle attached to the exterior end of the stem. The user is able to rotate the handle causing a corresponding rotation of the ball inside the valve housing. In a first orientation of the ball, the aperture therethrough is aligned with the inlet and outlet openings allowing the fluid to flow through the valve. When the handle is rotated ninety degrees from the first orientation, the aperture through the ball no longer is aligned with the inlet and outlet openings, instead a solid portion of the ball blocks fluid flow through the valve. The handle and the attached ball can be placed at other positions between the fully opened and fully closed orientations to throttle the flow of fluid through the valve.
In many applications of a ball valve, it is desirable to prevent unauthorized operation. Therefore, a locking mechanism is required to preclude moving the valve handle from the fully closed position without appropriate authorization. For example, when maintenance is being performed on equipment downstream from the valve, it is often necessary to lock the valve in a closed state to prevent someone from inadvertently opening the valve, thereby releasing hazardous energy resulting in harm to personnel or equipment.
Known valve lockout assemblies, such as disclosed in U.S. Pat. No. 5,415,017 which is assigned to the assignee of the invention disclosed herein and fully incorporated herein by reference, have proven very successful in the market. These prior art assemblies, however, require assembly proximal the point of use and are difficult to install onto a valve handle. Accordingly, a need exists for a simple valve lockout assembly that does not require assembly at proximal the point of use and is easy to install onto a valve handle.